Toggle clamp opening mechanism



Aug. 28, 1962 R. E. KREGER TOGGLE CLAMP OPENING MECHANISM Filed May 14,1959 ATTORA/EFS 1 Claim. (Cl. 81--351) This invention relates to animproved means for unlocking and opening the jaws of a toggle clamp ofthe conventional double jaw, dou-ble handle type.

The invention consists in the provision of an improved form and mountingof a release lever, which is positioned between the clamp handles whenthe clamp is locked, and in improved reaction surfaces on the handleswhich are engaged by the lever when it is moved toward either one of thehandles to produce unlocking movement of the locked toggle joint.Another feature of the invention is the provision of a simple form ofspring which is employed to normally urge the clamp jaws to openposition so that once the toggle joint is unlocked by the release leverthe spring imparts further opening movement to the clamp jaws to urgeand hold them in open position until returned to locked position bymanipulation of the handles.

In the present construction, reaction surfaces provided on the clamphandles define, when the clamp is closed, the sides of a slot locatedcentrally of the handles and extending from adjacent the common pivotbetween the handles towards their outer ends. The inner end of therelease lever is provided with an enlarged nose portion to fit in theslot and is held in position therein by link means connecting the innerend of the lever to the handle pivot. Fulcrum points for the lever aredefined by the outer ends of its enlarged nose portion. When the leveris actuated, this construction and mounting of the lever results in oneof the fulcrum points engaging the reaction surface of the handle towardwhich the lever is moved and pivoting thereon while simultaneouslysliding toward the handle pivot as the opposite side of the end of thelever nose portion engages the reaction surface of the other handle withan opposite pivoting and sliding movement. Unlocking of the toggle jointis produced by the combination of separating movement of the handlesaugmented by an opening force applied to the handle pivot through thelink connecting this pivot to the end of the release lever.

A preferred embodiment of the invention is shown in the accompanyingdrawings which consist of the following views:

FIGURE 1, a side elevation showing a toggle clamp in locked position;

FIGURE 2, a side elevation corresponding to FIG. 1 showing the sameclamp with the toggle joint thereof moved to unlocked position; and

FIGURE 3, a fragmentary sectional view taken along the line 33 of FIG. 1showing the mounting of the release lever.

The clamp illustrated is a conventional double jaw, double handle typehaving a pair of jaws and 11 which are interconnected by a jaw pivot 12.A handle 14 is pivotally connected to the jaw 10 at 15 and acomplementary handle 16 pivotally connected to the jaw 11 at 17. The twohandles 14 and 16 are pivotally connected to each other by a handlepivot pin 18.

Jaw 11 is provided with the usual adjustable threaded jaw member 20 anda lock nut 21 for securing it in desired position so that the pieces 22to be clamped are held between the pad 23 oi jaw 10 and the end of thejaw member 20.

A release lever 26 has a nose portion provided on the inner end 27thereof by a U-shaped member 28 which is 3,951,928 Patented Aug. 28,1962 rigidly secured to the handle and projects beyond the end 27thereof to define a transverse aperture 29. Link means in the form of abail member 30 is employed to position the release lever 26 between thehandles 14 and 16 with the inner end and nose portion of the leveradjacent the handle pivot 18, the bail member 30 being pivotallyconnected to the pivot pin 18 and to the release lever by engagement inthe aperture 29 thereof.

Each of the handles 14 and 16 is provided with -a reaction surface 32and 33 respectively, these reaction surfaces being in spaced opposedrelation to each other; and, when the clamp is in locked position asshown in FIG. 1, the reaction surfaces are parallel to each other andform the sides of a slot which extends outwardly from the handle pivot18 along a center line drawn through the center of this pivot and thecenter of the jaw pivot 12.

The clamp jaws 10 and 11 are normally urged in a direction of openingmovement about the jaw pivot 12 by a spring member 36 which in the formshown con- =sists of a generally U-shaped, torsion type of spring havinga pair of legs 37 and 38 and a central portion 39 which extendstransversely to each of the legs and has a length slightly greater thanthe thickness of the clamp. The

central portion of the spring is located in a notch 49 in the jaw member11 facing the handle 16 so that the leg 37 of the spring extends alongone face of the jaw 14) while the leg 38 of the spring extends along theopposite face of the jaw 11. Each leg of the spring is provided at itsend with an integral clip consisting of two right angularly disposedportions 42 and 43. The clip portion 42 extends across the inner surface44 of a jaw while the other portion 43 engages the side face of the jawopposite to that engaged by its respective spring leg.

In order to release the clamp from the locked position shown in FIG. 1,the release lever 26 is moved toward either one of the handles 14 or16.. FIG. 2 illustrates the unlocking action as the release lever 26 ismoved toward the handle 16. Upon initial movement of the lever from itsposition shown in FIG. 1 where the nose portion 28 thereof is rathersnugly engaged in the slot formed by the handle reaction surfaces 32 and33, the outer end corner 46 of the U-shaped nose portion 28 of the leverpivots or fulcrums on the reaction surface 33. At the same time, theopposite side of the end of the rounded nose of the lever at 48 reactsagainst the surface 32 of the opposite handle. As movement of the lever26 toward the handle 16 continues, the link member 30 swings about thehandle pivot 18 and the fulcrum point 46 slides along the reactionsurface 33 toward the handle pivot while the other contact point 418 ofthe release lever slides along the reaction surface 32 away from thehandle pivot. Simultaneous pivotal movement of each handle 14 and 16about its respective pivot 15 and 17 is produced and this unlockingmovement is augmented by tension imparted to the link 30 tending to drawthe handle pivot 18 away from the jaw pivot 12.

Once the handle pivot 18 has moved slightly beyond a dead centerposition between the pivots 15 and 17, the spring 36 takes over theclamp opening function and quickly moves the jaws 10 and 11 to theirwide open position. Thus, only a small amount of movement of the releaselever 26 is required-only enough to actually unlock the joint.

Since the outer corners 48 of the nose portion define the fulcrums ofthe lever 26, the U-shaped nose portion 28 is made only long enough togive opening movement of the handles to an unlocked relation of thetoggle pivots. Any excess length of the nose portion reduces themechanical advantage of the lever and is unnecessary because of thespring 36.

While preferred embodiments have been described above in detail, it willbe understood that numerous modifications might be resorted to withoutdeparting from the scope of my invention as defined in the followingclaim.

I claim: In a toggle clamp of the type having a pair of jaws pivotallyconnected by a jaw pivot and a pair of handles each of which is pivotedto one of the jaws and to the other handle at a common handle pivot toform a toggle joint which when locked retains said jaws in closedposition; means whereby said toggle may be released and the jawscompletely opened by a one-hand operation comprising a toggle releaselever and a detachable jaw opening spring adapted, when said togglejoint is unlocked, to drive said clamp jaws to open position and holdthem there; said spring having a pair of legs and a substantiallystraight central portion extending transverse thereto, said centralportion having a length in excess of the thickness of said clamp in adirection parallel to and adjacent the jaw pivot thereof, means fordetachably connecting said spring to said clamp comprising a notch inthe edge of one of the jaws between the jaw and handle pivots thereof,said spring being adapted to be threaded through said notch to place thecentral portion of said spring in said notch, with one of said springlegs extending outwardly along one face of one clamp jaw and the otherspring leg extending outwardly along the opposite face of the otherclamp jaw, each of said spring legs having a terminal portion whichextends across the clamp jaw inwardly thereof and into overlappingengagement with the jaw face opposite to that engaged by the leg.

References Cited in the file of this patent UNITED STATES PATENTS1,531,680 Stenerson Mar. 31, 1925 2,192,227 Hill Mar. 5, 1940 2,754,591Schweizer July 17, 1956 2,783,797 Blatt et a1 Mar. 5, 1957 2,799,191Barnes July 16, 1957 2,894,547 Lampe July 14, 1959

